777-200LR Flight Test Journal: Archives
27 July 2005
A bird's eye view
Paul Bolds-Moorehead, stability and control lead engineer, 777 program
Karen Alberghini, stability and control engineer
Tim Nelson, stability and control engineer
We sometimes refer to "stability and control" as one of the few groups, other than the pilots, to have an airplane-level view. How does the airplane fly? How does it behave? What does it feel like?
Other organizations are responsible for things like materials. The structures group 'owns' the metal and composites and assembles the airplane. Payloads knows about interiors. Our Aero Performance teammates know metrics and how the airplane can do certain things, but not how it flies at the edges of the envelope.
And we have a holistic view and make sure the 200LR flies just like other 777s. Our job starts with flight test and validation. One of the first things we do is work with pilots in the 777 simulator to make sure we're ready for flight. It's all part of a comprehensive safety review to satisfy requirements on how the airplane handles for safe behavior. We also meet critical internal Boeing design requirements and FAA/EASA certification regulations.
Here's Karen in front of the 200LR engine. The engine cylinder she is standing in is the same size as an entire 737 fuselage.
The stability and control team gets involved with maneuver sets that can go to the edges of the envelope. For instance, we simulate an engine failure and see how well we can control the airplane within certain parameters. We go beyond the normal maximum operating speed or Mach number. We fly at high altitude and do full stalls exceeding maximum lift coefficient.
Our group makes sure handling qualities are acceptable - both predictable and responsive for a safe handling airplane. To increase safety, we test in areas and perform maneuvers beyond where the airplane would normally fly. These maneuvers are not unique to the 777; they're generic to stability and control testing. They help us determine the characteristics of a particular model.
If we find handling qualities that require further tuning, the flight controls team can help tailor the flight control system by tweaking the software instead of modifying the airplane structure or hardware. Fly-by-wire is unique to the 777 family and greatly improved our ability to tailor characteristics both before and during the flight test program. The 787 will have the same benefit.
One of the hardest things to do on remote flight testing at Edwards Air Force Base in May and June was figure out what we were going to do next and be prepared. There are a lot of people who have to make decisions to get a test sequence put together for the next day. We're constantly trying to capture what we just did, look at the data and write the test summary. Then we have to get ready for tomorrow, all in a few hours. And by the way, we squeeze in a few hours of sleep, too!
And we're off for more flight testing.
Problem solving is probably the most stressful bit of our jobs, but it's the most rewarding, too. Working with the other groups and understanding more about what they do, how it affects us and how our work affects them can be challenging. Coming to a solution that works best for everyone and produces a great product is really the most satisfying aspect of our assignment.